Despite the long history of its use (ammonium succinate was known as the anticonvulsant medication of the 19th century, see H. O. Hager, Guide to Pharmaceutical and Medical-chemical Practice, Saint Petersburg, 1889, table 1, pp. 164-167), ammonium salt from fumaric and succinic acid is not available on an industrial scale (“Succinic Acid in Medicine, the Food Industry, and Agriculture”, M. N. Kondrashova et al., ed., Pushchino, 1996, p. 262). This article points out previously, ammonium succinate was used as a chemical reagent in the USSR at the Yerevan chemical factory and for the GDL at the VEB Laborchemie Apolda enterprise.
There are several known methods of obtaining preparative ammonium salts from these acids, such as the method for producing di-ammonium fumarate from fumaric acid and ammonia in a hot alcoholic solution described in the “Beil” handbook, table 2, suppl. 1, page 301.
The disadvantage of implementing this method on an industrial scale is the use of volatile solvents and ammonia gas, which has a safety limit of release for equipment working under pressure and requires power expenditure and cooling agents for the regeneration of the solvent.
A method of obtaining salts from succinic acid by hydrogenation of maleic acid salts in the presence of a palladium-nickel catalyst is described in RU Patent No. 2129540. According to this method, ammonium succinate is obtained from maleic anhydride and 24% aqueous ammonia as a result of hydrogenation of the formed di-ammonium salt of the maleic acid under hydrogen pressure of 15 atm at 80° C. in the course of 5 hours using a palladium-nickel catalyst.
The disadvantage of such a method is the use of expensive catalysts, pressurized equipment, and hydrogen, which calls for a huge expenditures for safety measures.
It is also known that one can obtain ammonium succinate of carboxylic acids, free from high yielding halogens, as well as the interaction of quarternary ammonium salts with acid metal salt in a mixture of water and alcohol with the distilled solvent (see JP2002-179614 and JP57-050937).
It is known that one can obtain ammonium and/or acid metal salt from di- and tricarboxylic acids for photographic processes of the reactions di or tricarboxylic acids or their anhydrides with ammonium and/or metal salt bicarbonate in the solid phase with the temperature of 40-100 C.° using polymers (see EP1284254A1).
Also, neutralization of oxalic acid, ammonium carbonate, by mixing these components in the equivalent parts of distilled water when exposed with mixing and filtering with a dried paste, is described in Alt-Photo-Process-L:Re:Sodium chloropalladite, www.usak.ca/lists/alt-photo-process/2004/jan04/0295.htm (January 2004). This method, in certain aspects, is similar to the proposed method for obtaining ammonium salts from dicarboxylic acids. However, there is no data on the quality of the output of the product obtained and the parameters of the division and drying. This method may only be used in laboratories.
A method is the method for producing an aqueous solution di-ammonium salt of succinic acid for the synthesis of succinimide is described by H. Clark and L. Berg (Synthesis of organic preparation, sb. 2, edition BLETT, foreign literature, M, 1949, c. 439). The method includes the following stages:
236 grams (2 mall) of succinic acid is placed In a 1 liter Wurtz flask with a side outlet 236, and during cooling and shaking, 270 ml (243, 4 Mol) 28% aqueous ammonia specific weight (0.90) is slowly poured. With that, most of the acid dissolves, forming a clear solution of di-ammonium salt. The solution is subjected to distillation and decomposition to yield succinimide as a result of salt decomposition. However, there is no data in this publication showing the temperature of the reaction, the rate at which ammonia solution was added, the method of salt extraction, the parameters of salt drying, or the quality of the obtained di-ammonium salt from succinic acid.
The Clark et al. reference does not contain any information concerning the reaction temperature range, rate of introduction of aqueous ammonia, salt extraction method, salt drying mode, quality of the resulting di-ammonium salt of the succinic acid. The thermal instability of ammonium succinate (see R.J.Chem. 1989, 43110 [WHAT?]; Thermochim. acta—1988-132.—pp. 229-233 Engl.) which dissociates at 360° K or 87° C., requires performance of a multistage vacuum drying for the salt production from its aqueous solution. In the process of producing salt from succinic acid and a 20-28% aqueous solution of ammonia, the resulting salt is in the form of a ˜45% aqueous solution at 0°. In order for separation to occur there must be a multi-stage steaming of the salt under a vacuum because with a temperature of over 80° C., there is a possibility of the formation of succinimide accompanied by resinification. As a result of this separation, the salt takes on a beige tint. In addition, the organization and maintenance of an evaporation plant requires a large expenditure of energy and coolants. In the description of the method, there is no evidence about the yield of the salt products. Therefore, this well-known method for obtaining ammonium succinate is meant solely for laboratory usage.
The object of the proposed method is to come up with a more adequate means for obtaining ammonium salt (mass no more than 99% and yield under 98%) from succinic and fumaric acids in a “green” manner for industrial production. This would increase the yield of target products and ensure their consistent high quality.
The object is achieved by obtaining ammonium salts from fumaric or succinic acid by neutralizing the corresponding acid-neutralizing compound in an aqueous medium. The difference between this method and the conventional one is the use of a neutralizing compound carbonate or ammonium bicarbonate at a molar stoichiometry or stoichiometry greater than a 4-5% ratio of acid and carbonate or ammonium bicarbonate, and performing neutralization in a saturated aqueous solution of the synthesized salt at a temperature not exceeding 40° C., followed by separation of the product and drying at a temperature not exceeding 70° C. The filtrate can then be recycled after the separation of the ammonium salts.
Isolation of the product is usually carried out by cooling the reaction mixture to a temperature of 15-18° C., with the product coming out in a predominantly crystalline form.
Saturated aqueous solution of the synthesized salt is prepared interaction carbonate or ammonium bicarbonate with the appropriate acid at a temperature not exceeding 40° C.
A more detailed process is described below:
(1) Mono-ammonium salt (fumarate or succinate) is derived from carbonate or ammonium bicarbonate and the corresponding acid in a molar ratio, respectively, 0.52/0.05:1 or 1.4/1:1;
(2) Di-ammonium salt (fumarate or succinate) is derived from carbonate or ammonium bicarbonate and the corresponding acid in a molar ratio, respectively, 4.1/4:1 or 2.1/2:1;
(3) Neutralization is brought to saturated form with a temperature of 18-20° C. solution of the synthesized salt;
(4) The optimal temperature of neutralization is 40° C.;
(5) The optimum dosage of succinic or fumaric acid (or ammonium carbonate and bicarbonate) is determined by the volume of foam above the level of suspension in the reactor (less than ⅓ of suspension) and lasts no more than 2 hours;
(6) Optimal time of exposure after dosing—1-2.5 hours at a temperature of 40° C. and depends on the device (the greater the volume, the greater the exposure);
(7) Final crystallization of sediment is carried to a temperature of 18-15°;
(8) Temperature for the sediment to dry is less than 70° C.;
(9) Ammonium bicarbonate is the preferred neutralizing agent, since it has a higher temperature of decomposition in comparison with ammonium carbonate;
(10) The filtrate is returned for recycling.
The proposed method can be broken down into the following:
With a temperature up to 40° C., in a saturated solution of synthesized salt (at 18-20° C.), carboxylic ammonium salt is charged and given dicarbonate acid in synthesis (upon formation of mono-ammonium salt bicarbonate or ammonium carbonate, carbonic acid is dosed in suspension) in the course of 2 hours, followed by exposure for 1-2.5 hours at a temperature not exceeding 40° C. and cooling the suspension to a temperature of 15-18° C. The precipitate is filtered on a vacuum filter and dried at a temperature not exceeding 70° C. until the smell of ammonia has subsided. The filtrate is then recycled. Targeted salt is obtained with a yield of 98-100%, containing molecules with a mass not exceeding 99%. The products fulfill the requirement of biologically active food additives containing harmful dyes, including
Mass fraction of lead (Pb), % not more than5.0-10−4Mass fraction of arsenic (As, % not more than3.0-10−4Mass fraction of cadmium (Cd), % not more than1.0-10−4Mass fraction of mercury (Hg), % not more than1.0-10−4
IR spectroscopy confirmed the structure of salt and set them a high degree of purity. The assignment of bands in the infrared spectra of the main structural elements is held in accordance with the published data (L. Bellami, Infra-red spectrums of complex molecules, M., IL, 1963, p. 592; K. Nakanisi, Infrared Spectrums and the Formation of Organic Compounds, M., Mir, 1985, p. 216).
The invention is further illustrated by the following examples: